The present invention relates to wireless systems, and in particular, to the problem of assigning reporting slots to nodes on a wireless mesh network.
Wireless networks, such as those operating according to IEEE 802.11 standards typically provide wireless packet-based data services to clients in a network. These clients may include computers such as laptops, hand-held devices such as smart phones, scanners, and the like, as well as wireless infrastructure devices such as sensors and cameras. In one common implementation, a plurality of wireless access nodes, each typically a small purpose-built computer system with one or more wireless interfaces, also includes a wired interface such as IEEE 803.2 Ethernet, to connect the access node back to a controller, which provides access to network services, as well as optionally providing functionality such as authentication, security, advanced mobility, and the like. In such a network, clients establish a wireless connection with an access node. Traffic to and from the client is passed to and from the access node wirelessly, and to and from the access node and the controller through the wired connection.
There are circumstances in which it may be difficult or expensive to run a data connection between each wireless access node and a controller. Mesh networks are useful in such circumstances. In a mesh network, rather than having each node wired to a controller, wireless access nodes establish wireless connections with each other, with only a small number of access nodes having wired access to a controller. In such a mesh network, clients also establish a wireless connection with an access node. But rather than traffic going wirelessly from client to access node, and from there by wired connection to the controller, in a mesh network, traffic first passes wirelessly from client to a first access node, and then wirelessly from that first access node through one or more other access nodes in the mesh network, until the traffic arrives at a root node or mesh portal, a wireless node which also has a wired connection to the controller, and from there to the controller. The mesh connection between access nodes may be through the same radio system and/or same radio channels as used by client traffic, or a separate radio and/or band as used by client traffic.
As is known to the art, mesh networks may be self-organizing, and adaptive, shifting their interconnections as access nodes enter and leave the network, or other characteristics of the network or its operating environment change.
It is common to represent mesh networks as a one or more trees, with each tree rooted at a root node or mesh portal. Topologically, these trees are cycle-free. Each access node forming a tree in a mesh network therefore has one parent it reports to and zero or more access nodes reporting to it as children.
In operation of a mesh network, there may be occasions where it is useful to have all access nodes report back to the controller. This may be for status, local operating parameters, or in the operation of a sensor network, reporting sensor data collected by the nodes.
To do this, nodes in the mesh network must report back, through the mesh network. One approach to doing this is to use the already existing contention resolution mechanisms in the network and let reporting from nodes be a free-for-all.
A more orderly approach assigns a reporting schedule or sequence to nodes on the mesh network. Such a schedule based access method provides for reduced latency, reduced collisions, and lowers overhead in sending and receiving of packets. This problem may be equated to “flattening” the mesh network and assigning a reporting sequence to the nodes in the mesh.
What is needed is a way to assign a reporting sequence to nodes in a wireless mesh network.